Let your reader be a fly on the wall
Regardless of how fantastical your plot may be, you want your reader to feel like a fly on a very real wall. You want them to feel like they're not just reading a story, they're stepping into a rich, colorful, fully-developed world and are spying on it for a while, if not stepping right into the shoes of your protagonist. I'm not a vampire, or an astronaut, or a twelve-year-old boy, and simply outlining what those beings are like isn't enough to grab my attention. What does is the magic that mixes our world and the other--the voice that connects "I know nothing about this" with "But I'd like to learn more" and "There's something about this that I can relate to". If an author doesn't put a piece of their own humanity into their story, doesn't "write what they know", it'll show and the story will be weaker for it. The plot will be there, but the life behind it will fall flat, lacking in the kind of compelling voice that engages us to keep turning the pages. There's nothing wrong with being inspired by other authors, but make sure your writing always comes from a place that's authentically you. Giving your story a real voice is the best thing you can do.